Weight lifting, power lifting, and body building have traditionally been individual sports wherein the person works out by himself using weights. Such weight devices can be very simple and basic like bar bells or more sophisticated like U.S. Pat. Nos. 4,426,636 to Angeli and 4,252,314 to Ceppo. In contrast to working against weights, there are also exercise devices in which two or more individuals work against each other rather than against dead weight. Examples of such devices are U.S. Pat. Nos. 2,937,023 to Seymour, 3,129,940 to Lauro, 4,284,274 to Boothe, 774,738 to Chavez, 3,069,169 to Samuel, 2,782,033 to Ugartechea, 4,220,328 to Crush, and 3,301,555 to Sicherman. Still other devices pit the individuals against one another through a braking arrangement such as U.S. Pat. No. 1,572,802 to Layman or team the individuals together against the braking force of the device such as U.S. Pat. No. 681,684 to Addeleman. Exercise devices are also available in which the individuals work out together but not against each other such as U.S. Pat. Nos. 4,047,714 to Powell and 3,743,280 to Martinez.
In regard to weight-free exercise devices such as Seymour, Lauro, and Boothe, they offer several fundamental advantages over working with weights. For example, there is the safety factor of not having weights which might fall or otherwise be mishandled and injure the user. Also, weights offer significant inertia and momentum particularly at the beginning and end of their movement whereas gradual increases and decreases in tension on the muscles are preferred. Such gradual changes can be offered in weight-free devices as the opposing individual can almost instantaneously respond to increases and decreases in tension applied by the other party. With weights and working alone, a person may have a tendency to cheat on a exercise as, for example, by jerking the bar up rather than bringing it up gradually. This may be particularly true if the lifter is near his limit on weight or repetitions. However, with weight-free devices such as Seymour, an individual cannot cheat as the other person providing the resistance will keep him honest. Weight-free devices also offer some variety to lifters who usually work out alone and such devices can additionally provide interesting one-on-one competition such as illustrated by Ugartechea. Further, particular muscles or portions of muscles can be exercised as desired by having the other person infinitely and instantaneously vary the resistance force at the proper time and in the proper amounts.
Although weight-free devices offer many advantages, they have to date been very limited in the number and type of exercises that can be done with them. That is, lifters have not been able to do the more traditional exercises (e.g., curls, leg extensions, presses) on such weight-free devices and the use of such devices has more or less been limited to tug-of-war type encounters such as illustrated by Seymour, Lauro, and Boothe. With this in mind, the present invention was developed wherein the exercisers can work against one another without weights and still do virtually all of the traditional exercises including curls, leg extensions, and presses. Further, the present invention in the preferred embodiment allows the exercisers to perform a wide variety of exercises on the same, basic apparatus with only a minimum of simple and quick adjustments to it.